1. Field of the Invention:
The present invention relates to a stretch film wrapping device, and, more particularly, to a device for rotatably supporting a roll of plastic film for tension stretch wrapping of objects, containers and the like.
2. Background of the Invention:
In shipping containerized goods, the general practice is to stack a plurality of the containers on a pallet and to utilize material handling equipment such as fork trucks to load and unload the palletized containers. To prevent containers from shifting or from falling off of the palletized load, it is generally required to band or wrap the palletized load. For example, metal or plastic straps or bands in conjunction with clips or buckles have been used for many years for this purpose. In recent years, there has been an increasing use of plastic stretch film to wrap and secure a palletized load of containers. The advantages of the use of plastic stretch film are enumerous. The stretch film produces a tight wrap and provides greater protection to the containers from damage due to harsh weather, abrasion, punctures and the like. The plastic stretch film is of relatively low cost and does not require the use of adhesives, clips or other fasteners.
While there are thus significant advantages to the use of plastic stretch film for wrapping palletized loads of containers, these advantages are not realized unless the wrapping procedure is properly executed. The two most important features of a proper wrap are the uniformity of the wrap and the proper tension of the plastic as it is applied. If the proper tension is not applied to the plastic there will be inadequate stretching of the plastic resulting in a loose wrap with poor holding qualities. In addition, the less the stretch of the plastic, the more the quantity of plastic which will be required, thereby resulting in a higher cost. On the other hand, if the tension on the plastic is too high, the plastic will rip and the advantages of a continuous wrap are lost. Random variations in the plastic tension during application can result in both ripped plastic and a loose wrap. Thus, the goal is to maximize the stretch without risk of tearing, while maintaining a constant predetermined tension during the wrapping procedure.
Although a variety of complex machines have been developed, their high cost, maintenance problems and lack of versatility have rendered them less than satisfactory in most instances. Because of this, a variety of hand held dispensers have been developed. The low cost, simplicity and portability of hand held dispensers would make them the ideal selection in most operations. However, heretofore, none of the hand held dispensers has been entirely satisfactory. To be satisfactory, a hand held dispenser must be durable, low cost and easy to use. Rolls of film must be easily and quickly replaceable. Most important, however, is that the tension adjustment for optimizing plastic stretch must be precise and consistent and produce uniform predetermined tension across the full width of the film for a uniform wrap. While various tension control devices have been developed, none has proven to be satisfactory. Tapered core plugs and other internal core friction devices such as expandable rubber gripping devices have proven to rely too much on the "feel" of the operator resulting in significant variations in the friction settings from operator to operator or from day to day with the same operator. In addition, precise and repeatable predetermined tension settings are not possible with these devices.
Other devices have utilized a pair of opposing core holders and adjusting the clamping force between the core holders on the plastic roll core ends to vary the tension. One such device utilizes a pair of rotatable core holders with the distance between the core holders being adjusted by means of a threaded rod and corresponding internally threaded tube interconnecting the core holders. Although once properly set, this type of device yields relatively uniform tension on the plastic, precise and consistently reproducable predetermined tension settings have not been possible.
Thus, there remains a current need for a hand held stretch film wrapping device which permits precise tension adjustments and consistent reproducable predetermined tension settings.